For use as nuclear fuel, enriched uranium hexafluoride is converted into uranium dioxide (UO2) powder that is then processed into pellet form. The pellets are then fired in a high temperature sintering furnace to create hard, ceramic pellets of enriched uranium. The cylindrical pellets then undergo a grinding process to achieve a uniform pellet size. The pellets are stacked, according to each nuclear reactor core's design specifications, into tubes of corrosion-resistant metal alloy, called cladding. The tubes are sealed to contain the fuel pellets; these tubes are called fuel rods.
Nuclear fuel swelling of Uranium Dioxide-based fuels (and possibly other nuclear fuels) is a life limiting phenomenon controlling the residence of nuclear fuel assemblies in the core of current Light Water Reactors (LWRs).
Current strategies for prolonging the residence time of nuclear fuel assemblies reactor cores consist of leaving a gap between the fuel pellet and the surrounding cladding that the nuclear fuel can expand into, and modifying the oxygen content away from stoichometric ratios to help control the rate of swelling.